This application claims priority of Japanese Application No. 2000-220974 filed Jul. 21, 2000, the complete disclosure of which is hereby incorporated by reference.
This invention relates to an ion selective electrode favorably employable for analysis of ionic components in a whole blood sample or a serum sample.
An ion selective electrode is widely employed for analyzing ionic components in a liquid sample such as a whole blood sample or a serum sample.
U.S. Pat. No. 4,571,293 (which corresponds to EP 0 160 997 B1) discloses an ion selective electrode which is illustrated in FIG. 6 of the drawings attached to this specification. In FIG. 6, the ion selective electrode comprises a non-electroconductive support 11, a pair of electrodes each of which comprises a silver metal layer 12a, 12b and a silver halide layer 13a, 13b, an electrolytic material layer 14, an ion selective membrane 15, and a non-electroconductive cover sheet 16 having a pair of openings 17a, 17b for receiving a sample solution and a reference solution, respectively, each opening being placed above each electrode unit, and having thereon an a bridge member 17 for electrically connecting the sample solution received in one opening and the reference solution received in another opening.
In industry, the ion selective electrode such as that illustrated in FIG. 6 is generally manufactured in a mass scale, by the steps of:
preparing a continuous longitudinal polymer sheet having thereon a composite film of a silver metal layer and a silver halide layer, and an electrolytic material layer, in order, in which the composite film is divided into two electrically insulated portions by a slit extending in a longitudinal direction thereof and further into plural electrically insulated units by slits extending in a direction traversing the longitudinal direction;
coating an ion selective membrane over the electrolytic material layer;
placing a non-electroconductive sheet having a pair of openings and a bridge member under the condition that each opening is placed on each spot of ion selective membrane; and
separating the continuous longitudinal polymer sheet, the electrolytic layer, the ion selective membrane, and the non-electroconductive sheet along the slits extending in the traverse direction.
The above-described industrial method is advantageous for manufacturing a great number of ion selective electrodes in a mass scale.
U.S. Pat. No. 4,789,435 describes an ion selective electrode assembly comprising plural ion selective electrodes for analyzing plural ionic components such as Na+, K+, and Clxe2x88x92, simultaneously. In the assembly, one of plural ion selective electrodes has an ion selective membrane differing from that of other ion selective electrode in chemical composition.
The ion selective membrane comprises a combination of specifically selected materials, and the materials are very expensive.
It is an object of the present invention to provide an ion selective electrode having satisfactory analytical performance at a relatively low production cost.
The object of the invention also resides in providing a method of manufacturing ion selective electrodes having satisfactory analytical performance in a mass scale at a relatively low production cost.
The present invention resides in an ion selective electrode comprising, in order, a non-electroconductive support, a pair of electrodes each of which comprises a silver metal layer and a silver halide layer, an electrolytic material layer, an ion selective membrane, and a non-electroconductive sheet having a pair of openings for receiving a sample solution and a reference solution, respectively, each opening being placed above each electrode, and having thereon a bridge member for electrically connecting the sample solution received in one opening and the reference solution received in another opening, which is characterized in that the ion selective membrane is divided into two separate portions, one of which is placed in a position above one electrode and another of which is placed in a position above another electrode.
The ion selective electrode of the invention is preferably manufactured in a mass scale by the method comprising the steps of:
preparing a continuous longitudinal polymer sheet having thereon a composite film of a silver metal layer and a silver halide layer, and an electrolytic material layer, in order, in which the composite film is divided into two electrically insulated portions by a slit extending in a longitudinal direction thereof and further into plural electrically insulated units by slits extending in a direction traversing the longitudinal direction;
placing a spot of ion selective membrane on the electrolytic material layer in a position above each insulated composite film;
placing a non-electroconductive sheet having plural pair of openings and bridge members under the condition that each opening is placed on each spot of ion selective membrane; and
dividing the continuous longitudinal polymer sheet, the electrolytic layer, and the non-electroconductive sheet along the slits extending in the traverse direction.